1. Field of the Invention
This invention relates to integrated circuits fabricated using glass isolation techniques and in particular to an integrated circuit fabricated using such techniques wherein the surface of the glass formed in the isolation grooves is substantially flat.
2. Description of the Prior Art
The use of oxide for isolating islands of semiconductor material in which are formed active devices is well-known. Thus, U.S. Pat. No. 3,648,125 on an invention of Peltzer discloses the basic oxide isolation technique now commonly employed in the manufacture of high density fast integrated circuits. Two problems with prior art oxide isolated structures of the types disclosed in the '125 patent are 1) the grown oxide encroaches into the active regions of the devices, and 2) the interconnection of the active devices becomes more difficult due to surface irregularities in the isolating oxide. Thus in the standard oxide isolation technique wherein a groove is formed in epitaxial silicon and the resulting exposed silicon is oxidized, a "bird-beak" is well-known to form at the intersection between the semiconductor material in which active devices are to be formed and the oxide isolation regions. While in most oxide isolated semiconductor devices manufactured prior to the filing date of this specification, this bird-beak is not an insurmountable problem, as the active devices become smaller, this bird-beak becomes a greater hindrance to the achievement of high yields.